1. Field of the Invention
This invention relates to a synergistic combination of three fungicides, boron-containing compounds, organo-iodine compounds and amine oxides, which when used in combination, give a synergistic result in providing improved resistance to mold, mildew and fungal decay on wood treated with this combination. Wood treated with this combination, and a method of treating wood, are also included in the present invention.
2. Description of the Prior Art
Wood is one of the best structural materials for the construction of buildings because of its strength, ease of processing and relatively low cost. However, wood and wood-based materials, including cellulosic composites and plastic-wood composites, are susceptible to both structural and cosmetic damage from fungal decay, mold and mildew.
Currently, a variety of fungicides including boron compounds are available to protect wood and wood composites from decay. For example, it is known to use zinc borate to protect cellulosic composites, including particleboard, hardboard and oriented strandboard, from fungal decay, as described in U.S. Pat. Nos. 4,879,083; 5,763,338; and 5,972,266. Zinc borate is usually applied as a powder or a liquid suspension to wood chips or strands, prior to their fabrication into panels. However, zinc borate is not a very cost-effective wood preservative, and does not provide good protection against mold, mildew and staining fungi at typical use levels.
It is also known to use iodopropargyl derivatives such as 3-iodo-2-propynyl-n-butyl carbamate (IPBC) for protection against fungi which cause structural and cosmetic damage to wood. However, while effective, this compound used alone is expensive and requires larger amounts to achieve the desired end result.
U.S. Pat. No. 5,389,300 provides a composition for protecting sawn timber against wood discoloring fungi, containing a phenol fungicide and an organo-iodine fungicide such as IPBC. Other fungicides, insecticides, or active ingredients, including boron compounds, can be added to the composition.
U.S. Pat. No. 5,846,305 discloses a wood preservative composition comprising a copper compound, an amine solvent and a boron compound. The preferred boron compound is sold by U.S. Borax, Inc. under the tradename xe2x80x9cTIM-BOR.xe2x80x9d
U.S. Pat. No. Re 36,798 provides a preservative composition for treatment of wood and other cellulosic materials, comprising a biocidal metal compound and a fungicidal compound containing a triazole group. Compositions of this invention may contain other organic fungicides, insecticides, or bacteriocides, including boron in any form, such as boric acid, boron, or boron esters.
U.S. Pat. No. 4,950,685 relates to a wood preservative composition which provides stain resistance to wood. The composition comprises a synergistic combination of a quaternary ammonium compound and IPBC.
U.S. Pat. No. 5,990,043 relates to an anti-fouling composition which includes a carrier, a binder, and an effective amount of at least one insecticide, which can be a carbamate. Synergistic effects are observed when combinations of two or more of the numerous insecticides listed are used in combination.
It is desired, therefore, to develop a wood treatment substance capable of protecting wood against fungal decay, mold and mildew in an economical manner.
The present invention fulfills the above need by providing an unusually effective and economical wood treatment that protects wood and wood products against fungal decay, mold and mildew. The present invention provides a unique combination of three classes of fungicides, specifically boron-containing fungicides, organo-iodine fungicides and amine oxide fungicides, which in combination provide a more complete resistance to decay, in a more economical manner, than use of any of these compounds individually. A method of treating wood, in particular composite wood materials, with the synergistic combination is included in the present invention, as is the wood treated by this combination.
It is an object of the invention therefore, to provide a combination of fungicides to resist decay in wood treated with such substances, in an economical manner.
It is a further object of the present invention to provide an economical wood treatment which can resist decay using boron-containing fungicides in combination with organo-iodine and amine oxide compounds.
It is an additional object of the present invention to provide a method of treating wood using this synergistic combination of fungicides.
It is an additional object of the present invention to provide wood treated with a synergistic combination of fungicides.
These and other objects of the invention will become apparent from the following description and appended claims.
Accordingly, the present invention provides a wood treatment material comprising a synergistic combination of a boron-containing fungicide, an organo-iodine compound and an amine oxide compound. As used herein, the term xe2x80x9cwood treatment materialxe2x80x9d refers to this synergistic combination of fungicides, which may be used with other additives such as resins or solvents, and which is applied to wood by a variety of methods including, but not limited to, spraying, dipping, pressure treating, addition during formation of engineered wood, and other methods used to apply such substances to wood and are known to those skilled in the art.
As used herein, the term xe2x80x9cboron-containing fungicidexe2x80x9d includes fungicides containing at least one boron compound selected from the group including boron, alkali metal salts of boron, alkaline earth metal salts of boron, metal salts of boron, oxides of boron, boric acid, boric acid esters and salts of these. It is thought that in respect to the metal salts of boron the active part of the compound is the boron, rather than metallic, portion.
As used herein, the term xe2x80x9corgano-iodine compoundsxe2x80x9d refers to a category of organo-iodine compounds known to have biocidal activity and to provide protection against fungi when applied to wood and other materials.
Examples of organo-iodine compounds which may be used in the present invention include, but are not limited to, iodopropargyl derivatives including compounds derived from propargyl or iodopropargyl alcohols such as the esters, ethers, acetals, carbamates and carbonates and the iodopropargyl derivatives of pyrimidines, thiazolinones, tetrazoles, triazinones, sulfamides, benzothiazoles, ammonium salts, carboxamides, hydroxamates, and ureas. This class of compounds has the general formula: 
wherein R is selected from the group consisting of hydrogen, substituted and unsubstituted alkyl groups having from 1 to 20 carbon atoms, substituted and unsubstituted aryl, alkylaryl, and aralkyl groups having from 6 to 20 carbon atoms and from substituted and unsubstituted cycloalkyl and cycloalkenyl groups of 3 to 10 carbon atoms, and m and n are independently integers from 1 to 3, i.e., m and n are not necessarily the same.
Preferred are formulations where m is 1 and n is 1 having the following formula: 
Suitable R substituents include alkyls such as methyl, ethyl, propyl, n-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, octadecyl, cycloalkyls such as cyclohexyl, aryls, alkaryls and aralkyls such as phenyl, benzyl, tolyl, cumyl, halogenated alkyls and aryls, such as chlorobutryl and chlorophenyl, and alkoxy aryls such as ethoxyphenyl and the like.
Compounds of this formula include iodopropargyl carbamates such as 3-iodo-2-propynyl propyl carbamate, 3-iodo-2-propynyl butyl carbamate, 3-iodo-2-propynyl hexyl carbamate, 3-iodo-2-propynyl cyclohexyl carbamate, 3-iodo-2-propynyl phenyl carbamate, and mixtures thereof. Most preferred is 3-iodo-2-propynyl butyl carbamate (IPBC).
As used herein, the term xe2x80x9camine oxide compoundsxe2x80x9d refers to those compounds which are formed as reaction products in the reaction of tertiary amines and hydrogen peroxides and are represented by the general formula: 
where R1, R2 and R3 are independent and can be straight or branched, saturated or unsaturated carbon chains from 1 to 20 carbons in length.
Preferred amine oxides are alkyl dimethyl amine oxides such as decyl dimethyl amine oxide, lauryl dimethyl amine oxide, isoalkyl dimethyl amine oxide, myristyl dimethyl amine oxide, cetyl dimethyl amine oxide, stearyl dimethyl amine oxide and octyl dimethyl amine oxide. Most preferred is N-alkyl-N, N-dimethylamine oxide (ADO).
As used herein, the term xe2x80x9cwoodxe2x80x9d includes a variety of wood and wood-based materials, including but not limited to logs and other types of dried lumber, green lumber, fiberboard, strand board, laminated veneer lumber, cellulosic composites, plastic wood composites and other types of wood, wood composites and engineered wood formed from wood flakes, chips, strands, veneers and adhesives.
In a method of creating the wood product, the fungicides can be applied on the surface of the wood, as in spraying or dipping the wood in a suspension containing all three fungicides. Typically, the organo-iodine compound and the amine-oxide compound are pre-mixed with solvents in a ratio of about 4 parts organo-iodine compound, 27 parts amine-oxide compound and 6 parts solvent (the remaining 63 parts consists of inactive material due to the manner of packaging active ingredients for sale). Any organic solvent can be used, but polar organic solvents are preferred as they will provide better solubilization of the organo-iodine compound. Most preferred are solvents such as dimethyl sulfoxide and dipropylene glycol.
Other constituents of the solution may include wax emulsion or other water repellant, solvents and/or water. The fungicides can also be applied to the wood with pressure treatment that is commonly used on solid or engineered wood. A third method, particularly for plywood, is to treat the wood chips, flakes or strands with the fungicide combination in powder or liquid form prior to formation of the composite wood boards. Wood may be treated by more than one of these methods, and as used herein the term xe2x80x9ctreatmentxe2x80x9d refers to any one of these or other methods known to those skilled in art and which are used to apply these or similar substances to wood.
The wood treated by the composition of the present invention will have, on a weight to weight percent basis, a boron-containing compound present in the wood in an amount of about 0.1 wt. % to about 5 wt. %, more preferably about 0.2 wt. % to about 0.6 wt. %. The organo-iodine compound will be present in the wood in an amount of between about 10 ppm to about 1,000 ppm, more preferably between about 20 ppm and about 100 ppm. The amine-oxide compound will be present in the wood in an amount of between about 80 ppm to about 9,000 ppm, more preferably between about 200 ppm and about 600 ppm. All weight percent or part-per-million values are based on the total weight of the wood, either before or after high pressure treatment and excluding the weight of resins, waxes or other materials used in processing.
In the third method referred to above, the fungicides are combined with wood flakes, chips or strands, an adhesive such as a phenolic or isocyanate resin or other similar resin known to those skilled in the art, and a water repellant and fabricated into a wood composite board. This last step may be accomplished in a heated high-pressure press. These severe processing conditions often result in reduced performance of additives such as fungicides. Unexpectedly, the performance of a boron compound in combination with an organo-iodine compound and an amine-oxide compound was not reduced, but was actually improved. This combination of fungicides has proven to be unusually effective in providing resistance to decay, mold and mildew.